Perhaps, in hindsight, they got a bit cocky. Perhaps things had been going too well.
A typical mission on the Shrieking Shack (a ship that was the pride and joy of the Marauders, even if it did make a terrible shrieking sound whenever it took off or landed), went like so:
They would get their cargo together somewhere far enough out of the Death Eater’s clutches that they didn’t face any risk for buying bulk orders of medicine suitable for human use (thankfully, it had other uses too, or it simply would’ve disappeared off the market completely) and human-digestible food. They made sure to buy plenty of stuff that was considered “luxuries” — chocolate, new toys, nice clothes. Word was that since the blockade of human systems, their economy had crashed because they could no longer export anything and they no longer had the resources to produce things the rest of the galaxy took for granted.
They loaded up their hold with the stuff they had plausible deniability for (the really boring standard stuff, like Galactic Standard Cheese and weak analgesics) and filled their secret compartments with the more exciting cargo. They had a contract with Frank Longbottom’s uncle’s medipack factory which got them into the system just fine, and they would land at different places every second trip or so — technically their contract was for a specific facility on Hudders 413, but they didn’t want to put anyone in danger by forcing them to create big underground supply networks to distribute the contraband goods. If they got caught in the wrong place, they could probably walk it off; humans might not be so lucky.
So they arrived at the Hudders 413 facility or somewhere else — always a medical facility for plausible deniability; they had documentation they could quickly change the details of that made it look like they were re-routed by Frank’s uncle at the last minute. The legitimate cargo was unloaded (always very slowly, of course, with plenty of checking that the medipacks were still good and had absolutely no cracks in them from the flight in) and the humans who assisted with the unloading also took the contraband, either packed under the medipacks or occasionally just in their pockets.
It was fulfilling work and surprisingly easy. Of course they had a whole system of code set up with Frank’s uncle, and James always felt nervous between the time they spotted the blockade to when they got through it, but really it was just driving a ship in between two points in space and seeing the joy on children’s faces when they saw chocolate for the first time in a year.
The fact that James couldn’t really talk about it without Lily’s face going sad and wistful was a small price to pay. At first he thought perhaps she’d like news of home, though he never saw her family and made sure not to go near their settlement, in case the worst should happen. She was never angry at him, but she was always distant and melancholy for the rest of the night, so he stopped doing it. He wanted to take her along probably as much as she wanted to go, but it was far too dangerous — she might not be let back through the blockade if something went wrong.
And it would go wrong eventually. It did go wrong. They got through the blockade just fine: the people on the blockade had got used to them, since they were such familiar faces, and it felt more like a formality than anything to ask for the ship’s ID and their papers. The first hint of what was to come was the communication they received from Frank’s uncle, which said that there was no need to re-route after all, and they should land in the usual place. This had happened before — if the Death Eaters were feeling particularly jumpy, or Frank’s uncle was feeling particularly jumpy, he would tell them to divert to their official facility rather than the planned “re-routed” destination.
None of them thought anything of it.
The Death Eaters arrived when they were halfway through unloading. The Marauders weren’t stupid, as much as they appeared to be cocky youths too sure of their own immortality: they had decoy clean medipack boxes, and they had procedures in place, they had run drills. It was very different executing them in real life, when the bad guys had not set their guns to stun.
(One of the problems of the pre-approved code was that there was no ability to add nuance to it — were the Death Eaters here because they were just being hypervigilant across the system at the moment, or was the earlier message a betrayal? They certainly didn’t have time to question it now.)
At first it went fine. Out came the clean medipack boxes; nothing to see here, officer. The problem came when one of the children greeted Sirius with a little too much familiarity. Her mother grabbed her immediately afterwards, but the deed was done. A Death Eater got up in Sirius’s face, asking why he knew humans well enough for children to hug him; Sirius tried to insist that it was because he was fluffy, and children thought it was delightful that he was so soft, since humans only had hair on their heads.
Remus could tell the Death Eater didn’t buy it the moment he brought out his gun, and ordered James to start the engines. Thankfully, humans had stopped helping unload the moment the Death Eaters had turned up, so it was just a matter of Sirius dodging beams that left scorch marks behind and racing far enough into the hold that James could close it up and get ready for takeoff.
The main problem facing them now was that they could hide cargo much more easily than they could hide extra guns. They had guns on their ship — space was dangerous, after all, and it was reasonable to have some weaponry to defend your cargo from pirates — but there was a difference between “I have a plausibly explainable number of guns” and “this is a gunship”. The Death Eaters had gunships.
Thankfully, even if the Shrieking Shack was not anywhere near a top of the line ship, it handled quite well, especially in the hands of an excellent pilot. (James Potter was not afraid to toot his own horn about that one — he’d worked bloody hard for it.) As he dodged and weaved and zagged he repeated to himself over and over that all they had to do was get out of atmosphere and they could hyperjump. They could do that. They could survive that long.
There was an almighty bang as one of the Death Eaters’ shots hit true and James saw a warning light flicker to life on the dashboard. Shit. Banking hard to the left to avoid yet another gunship that appeared from who-knows-where, he called over the intercom, “I bloody well hope you’ve strapped yourselves in.” There was no response, but he didn’t expect there to be; he could only hope he hadn’t accidentally broken all of Remus’s limbs or given Sirius a grievous head wound. (Peter, thankfully, was celebrating a holiday with his family. You could break his bones by looking at him wrong.)
An alarm sounded as they took another hit, but James imagined he could almost taste how close they were to safety. As the steering started to go, with him entirely unable to stop the ship veering left no matter what he tried, the light finally came on that indicated they were safe to hyperjump. He smashed it immediately and prayed that nothing that had been damaged was essential for this process. As he was slammed back into his chair by the g-force, he thought for a moment of Lily, of his family, of what would happen if the ship disintegrated in hyperspace.
At least they’d die doing something worth dying for.
He had tensed for something catastrophic to happen, but instead they emerged on the other side safely, in the outer reaches where Death Eaters didn’t care enough to establish any kind of influence. The ship was still listing ever to the left, there was still an alarm sounding that he hadn’t actually worked out the source of and he had no idea whether they’d ever be able to do another supply run again, but for now, they had survived.